Batgirl and Supergirl must team up to break into Arkham Asylum! In this all-new Rebirth annual Batgirl must seek Supergirl’s help to solve a mystery that leads them to the heart of the most insane insane asylum there is!

Batgirl and Supergirl must team up to break into Arkham Asylum! In this all-new Rebirth annual Batgirl must seek Supergirl’s help to solve a mystery that leads them to the heart of the most insane insane asylum there is!

But what they discover - and who they discover - in Arkham will lead to a much, much bigger story!